Who ran the Russian government after czar Nicholas II?

After Nicholas II was arrested, the politicians in the Duma decided to give a lead to Russia. They set up the 'Provisional Government' until elections could be held later in 1917 for the 'Constituent Assembly.' The Constituent Assembly was intended to write a new constitution to govern Russia under a democratically elected government.

The Provisional Government was not very effective and did not satisfy the revolutionary demands of the soldiers, workers and peasants. When the Provisional Government lost the support of the people, Lenin and his Bolsheviks took power from the Provisional Government. The Bolsheviks survived the Russian Civil War and retained power from then on.